We should insert a word of caution regarding the diagnosis of influenza among troops in the absence of any sign of an epidemic. Internists who served in base hospitals during the war will agree that a diagnosis of influenza is very frequently made on the admission card when the disease turns out to be some other malady. This was not equally true in all camps, but regimental surgeons could often be found who would transfer a patient to the hospital with the diagnosis of influenza used almost interchangeably with the diagnosis “Fever of unknown origin.” It would be interesting to see statistics from one or two of those base hospitals which were manned with especially competent internists, as to the frequency with which the admission diagnosis of influenza remained unchallenged in the hospital, during the year 1917. There would be such cases in greater or smaller numbers. The magnitude of this number would not influence our hypothesis. Aside from this discussion of the disease among our troops in France it is most important that we establish, if possible, the identity of the disease reported among British troops in Northern France during the winter of 1916–1917 and designated by the name “Purulent Bronchitis.” The disease first appeared in December, 1916. It reached its height during February and early March of 1917, and appears to have disappeared early in the spring. Hammond, Rolland and Shore report that during February and early March 45 per cent. of the necropsies under observation showed the presence of purulent bronchitis, and they remarked that the disease assumed such proportions as to constitute almost a small epidemic. They described the clinical aspects as follows: “The cases which came under our notice can be divided broadly into two types: The first and more acute presents a clinical picture which closely simulates ordinary lobar pneumonia with a sustained temperature of about 103°, and expectoration at first blood-streaked—rather than rusty—which, however, rapidly becomes quite purulent. The pulse-rate in these cases is out of all proportion to the temperature in its rapidity. Dyspnoea and cyanosis are prominent features. The patient usually dies from ‘lung block,’ resulting in embarrassment of the right side of the heart on the fifth or sixth day. For the last day or two there is often incontinence of the feces, due, no doubt, to the condition of partial asphyxia. The mental state is one of torpor; delirium is the exception.